Changing Winter Climate Causing Permafrost Below Shallow Arctic Lakes to Thaw
A new study revealed that warmer winters and increasing snowfalls due to climate change is causing the permafrost below the shallow arctic lake.
According to the study published in Geophysical Research Letters, changing winter climates over the last 30 years have limited the growth of seasonal sea ice, leading to warming of lakebed temperature of Arctic lakes less than 1 meter deep by 2.4 degree Celsius. This makes the annual lakebed temperature to be above the freezing point.
This rate of warming was also observed in terrestrial permafrost. However, those soils are still well below freezing and are not expected to be thawed for another 70 years. The reason behind why terrestrial permafrost are not expected to be thawed anytime soon, while sub-lake permafrost are already being thawed is because of the warmer temperatures of permafrost under the lake.
And now, as the temperature in the lakebeds is continually rising, the permafrost underneath the lakes, which cover 20 to 40 percent of the landscape in vast areas of Arctic lowlands, are thawing at a faster rate than those beneath the surrounding dry land.
Reduction of lake ice due to warming temperature caused by climate change is the primary reason why the temperature in shallow lake beds are warming, causing the permafrost below them to thaw.
"With further thawing of sub-lake permafrost there is a good chance that the ground will subside, increasing the lake depth and accelerating further permafrost thawing. In contrast, the warming on the land may increase the protective vegetation layer and delay thawing of permafrost outside of lakes," explained Vladimir Romanovsky of the UAF Geophysical Institute and co-author of the new study, in a statement.
Researchers warned that shallow lakes will continue to warm due to the increasing warmer and snowier winters. They also noted that the thawing of permafrost can lead to the unlocking of some of its carbon pool, potentially releasing the carbon in the form of greenhouse gases.